'Tourists who attend a bullfight out of curiosity are often horrified to witness the violent, bloody reality of this archaic pastime.' Photograph: Ivan Aguinaga/AP

It's been said that our lies tell as much about us as our truths. And every day, we lie to ourselves about what's happening to animals in the world – their pain and suffering, and the part we play in causing both. In the days to come, dozens of bulls will be stabbed to death in Pamplona's bullring, a direct consequence of tourists' support of the running of the bulls.

Thrillseekers are heading to Spain to participate in the annual spectacle, keen on their own enjoyment but giving little thought to what the event actually means for the bulls. They see the charm of Pamplona's cobblestone streets but what they don't see, or don't want to see, is that the bulls have trouble navigating those narrow corridors, slippery with spilled beer and blood. As screaming spectators hit them with sticks and rolled-up newspapers, they careen into the walls and each other, fall and break their horns and bones, reaching the finish line bruised and dazed.

Reporters looking to spin this event as human interest filler rarely mention it, but the daily runs are simply the opening act before these magnificent animals are led into the bullring. Tourists who attend a fight out of curiosity are often horrified to witness the violent, bloody reality of this archaic pastime. Men on horses run the bulls in circles while repeatedly stabbing their necks and shoulders with knives until the bull is draped in a cape of blood. As evidence of a truly warped sense of honour, the matador comes in only for the killing plunge, when the exhausted and weakened bull is already on the verge of death.

Tourists who participate in the run or visit Pamplona simply to watch it contribute to the carnage. Every shared tapa, every cerveza, every booked hotel room and balcony bolsters the killing. As long as the city makes money off the event, bulls will continue to suffer and die.

Some Spanish aficionados are uniquely blind to the carnage, going so far as to propose – in a recent initiative currently under consideration by the culture committee of the Spanish congress of deputies – that this blood sport be granted legal protection as a "cultural pastime". In 2013, in an otherwise civilised society, seeking such a designation for gratuitous slaughter is perverse.

Over the next few days, my friends at Peta will be forcing the Spanish government to acknowledge the body count by sending people to Pamplona to lie inside 48 coffins, in homage to the four dozen bulls who are killed every year at the Festival of San Fermín – just a fraction of the 40,000 bulls slaughtered annually in bullfights across Spain.

Ernest Hemingway saw his first bullfight in Pamplona in 1923, the same year that Albert Schweitzer's The Philosophy of Civilization was published. A jarring juxtaposition, indeed – one celebrating death, the other revering life. Hemingway, of course, went on to write Death in the Afternoon, his ode to bullfighting, whereas Schweitzer continued to provoke discussion about the very definition of good and evil, writing: "It is good to maintain and to encourage life; it is bad to destroy life or to obstruct it." In 2013, I would hope that Schweitzer's call for civility resonates more powerfully.

From pilgrimages to peyote, humans have always sought ways to find meaning in our lives. And so we should. But tormenting and butchering bulls for entertainment belongs to the dark ages – not the 21st century.